1. Field of the Invention
The invention relates to a method and system for determining when a projectile reaches a desired Height Of Burst (HOB) over a target based solely upon the time at which the projectile reaches or passes through the apogee or apex of its trajectory.
2. Description of Related Art
There are many types of projectiles that are designed to perform a function, such as detonation, at an optimal Height Of Burst (HOB) over a target. For example, an illumination round is designed to deploy a flare to spot enemy targets at night. Similarly, some smoke rounds are designed to burst at a specified HOB in order to obtain optimal dispersion of the smoke cloud over the target.
According to the prior art, a typical time fuse is used to function, i.e., detonate, the projectile when it reaches the desired HOB. A fairly complex set of parameters have to be entered into the system in order to accurately detonate the projectile at the desired HOB. First, the locations of the weapon and the target are required. Then a ballistics solution is computed to determine the angle it should be fired at; the velocity it should be fired at; and the time of flight at which the projectile will reach the desired HOB over the target. Other variables that affect the accuracy of this ballistics solution include meteorological conditions and propellant temperature. The complexity of prior art solutions increases the chances of error. Clearly a simpler and more robust method and system for determining accurately HOB over target is desired. It was in the context of the foregoing prior art that the present invention arose.